1. Field of the Invention
The present invention relates to a system and method for determining the measure of mobility of a subscriber device in an ad-hoc wireless network with fixed wireless routers and wide area network (WAN) access points. More particularly, the present invention relates to a system and method capable of determining the mobility of a node in a network, such as a wireless ad-hoc network that requires the node to share its information with other nodes, so that the rate at which the node shares this information could be based on the rate of mobility of the node, to thus enable the nodes to share their information with other nodes more economically from a bandwidth usage standpoint.
2. Description of the Related Art
In recent years, a type of mobile communications network known as an “ad-hoc” network has been developed for use by the military. In this type of network, each user terminal is capable of operating as a base station or router for the other user terminals, thus eliminating the need for a fixed infrastructure of base stations. Details of an ad-hoc network are set forth in U.S. Pat. No. 5,943,322 to Mayor, the entire content of which is incorporated herein by reference.
More sophisticated ad-hoc networks are also being developed which, in addition to enabling user terminals (mobile nodes) to communicate with each other as in a conventional ad-hoc network, include intelligent access points (IAPs) that further enable the nodes to access a fixed network and thus communicate with other user terminals, such as those on the public switched telephone network (PSTN), and on other networks such as the Internet. Details of these types of ad-hoc networks are described in U.S. Pat. No. 7,072,650 entitled “Ad Hoc Peer-to-Peer Mobile Radio Access System Interfaced to the PSTN and Cellular Networks”, issued on Jul. 4, 2006, and in U.S. Pat. No. 6,807,165 entitled “Time Division Protocol for an Ad-Hoc, Peer-to-Peer Radio Network Having Coordinating Channel Access to Shared Parallel Data Channels with Separate Reservation Channel”, issued on Oct. 19, 2004, the entire content of both of said patent applications being incorporated herein by reference.
As described in the patent applications referenced above, each mobile node in the ad-hoc network communicates its routing table information to its neighboring mobile nodes and stationary nodes, such as fixed wireless routers or IAPs, within its radio frequency (RF) range, to inform those neighboring nodes of, for example, its neighboring nodes, the IAP with which it is affiliated, and its ability to operate as a router. For instance, if a mobile node's battery or power supply begins to become exhausted, the person using the mobile node may want his or her mobile node to cease operating as a router, or to only operate as a router if no other suitable router is available, to conserve battery power, as described in U.S. Pat. No. 6,873,839 entitled “Prioritized-Routing for an Ad-Hoc, Peer-to-Peer, Mobile Radio Access System”, issued on Mar. 29, 2005, the entire content of which is incorporated herein by reference.
When a mobile node broadcasts its routing table to the other nodes within its radio frequency (RF) range, each of those other nodes store all or a relevant portion of this routing table information in their respective memory. Hence, the respective controllers in the nodes can determine whether to route packetized data to a particular node based on, for example, the node's neighboring nodes, the condition of the battery of that particular node, and so on. The ability of the mobile and fixed nodes (referred to generally as “nodes”) to broadcast this routing information to other mobile nodes enable the mobile nodes to make possible the “self-healing” characteristics of an ad-hoc network as described, for example, in U.S. Pat. No. 5,943,322 to Mayor and in U.S. Pat. Nos. 7,072,650, 6,807,165 and 6,873,839, referenced above.
As can be appreciated from the above, due to the mobility of the mobile nodes in the wireless ad-hoc network, their neighboring nodes, as well as their affiliation with IAPs, change from time to time. That is, in a fixed or non-mobile data network (wireless or wired), the sharing of routing information is simple due to the fact that the only time the information changes is when a node is removed from the network. However, in an ad-hoc wireless network of the type described above, the mechanism for finding nodes, and determining how to route packets to these nodes, becomes more difficult. For example, due to the constant changes in the locations of the mobile nodes that are moving, it becomes difficult for the mobile nodes and their neighboring nodes to continuously share and update their routing table information with each other. In order to share this change information, large amounts of information must be exchanged to facilitate the updating of each node's view of the network topology to maintain routing decisions as up to date as possible. The more mobile the network is, the more frequently this data must be exchanged between nodes, thus requiring consumption of large amounts of the available bandwidth.
However, as can be appreciated from the above, if the network were capable of determining the mobility of its mobile nodes, that is, how frequently any node is changing its neighboring nodes and its affiliation with an IAP due to its movement, the rate that node shares its information, such as location and routing table information, with other nodes (i.e., mobile node, fixed wireless routers and IAPs) can be set more commensurate to the node's movement. That is, if the node is moving frequently or rapidly, the node should share its information with other nodes more frequently, because this information is changing more frequently. Also, the rate at which the node needs to perform Geo-location updates that enables it to determine its own location, can be set to be more proportionate to the node's mobility. However, if a node is stationary, such as in a home or office, the node need not share its information with the other nodes very often, because such information remains basically the same, nor need it perform Geo-location updates.
Accordingly, a need exists for a system and method capable of determining the mobility of a node in a network, such as a wireless ad-hoc network that requires the node to share its information with other nodes, so that the rate at which the node shares this information could be based on the rate of mobility of the node, to thus enable the nodes to share their information with other nodes more economically from a bandwidth usage standpoint.